PA38 and C150/152 training longevity

[G_STRING]

As the title suggests, any one have any idea of how these aircraft can continue to be used as trainers in flying schools.

Given the fact that some of them can be around 40 years old, will there be difficulty in the future maintaining them, (parts, etc)?

Would be a shame to see their demise, as they are both great for the job

[mad_jock]

There is nothing out there that comes near them for training aircraft.

Folk will continue using them until they are all condemed. I fully expect C152's to be used in training until the day I die.

[Beethoven]

My only issue with them is the max all up weight. I am a Tomahawk owner and with my 12 stones and fuel to tabs (20 us gallons) the maximum weight of my passenger is 9 stones ! And that's without any baggage. I'm not sure how the 152 matches up but I suspect somewhat similar.

[S-Works]

Not to mention the cash cow they are in spare parts for the manufacturers. The cost of certifying them was recovered decades ago so the fees for issuing paperwork and the price of the parts is massive cash generation for little investment.

As with MJ, I expect to have them flying long after I am gone!

[Whopity]

Bear in mind that the PA38 has a spar life which usually signals the end. The 150/152 will go on much longer

[Mickey Kaye]

Sadly I agree with MJ there is nothing about that's up to the job.

We really need a Rotax mogas running powerplant mated to an airframe that's as robust as the C150/PA38.

What I really can't understand is why have none of the manufactures been able to come up with one. The market must be massive.

[mad_jock]

In the UK the rotax engines are a bit of a pain for schools.

Cracking for owners who are willing to hump fuel in.

But if you putting in 100 ltr plus a day into 3-10 aircraft and there is nothing but AVGAS available they are a pain in the arse to be honest.

And Beethoven I know I shouldn't say it but I would suspect that both the C152 and PA38's are the most regularly over loaded planes in exsitance.

[Genghis the Engineer]

Sywell has a lot of Rotax engined training aeroplanes.....


...... and a mogas pump!

G

[mad_jock]

Its the only way it can work.

As a matter of interest Genghis how do they actually work out the MTOW of a light aircraft?

[Pilot DAR]

how do they actually work out the MTOW of a light aircraft?

Generally, once the structure is qualified, the demonstrated rate of climb and stall speed, coupled with handling, will define the MTOW for a light aircraft.

[Genghis the Engineer]

Its the only way it can work.

As a matter of interest Genghis how do they actually work out the MTOW of a light aircraft?

In many ways, you go around in circles. It works something like this:

- First work out your design spec (performance, payload, internal size, equipment)

- Using charts and tables that are readily available in aircraft design textbooks, come up with rough figures for the masses of the major subsystems (wings, fuselage, cockpit, gear, powerplant...)

- Now start refining it by using some real components, particularly the engine, as there are only so many engines available and this tends to start dictating everything else.

- Go round the loop a few times to come up with more accurate estimates of size, shape, component list.

- Take the estimated empty weight and payload, add them up, add a bit more, and set this as your provisional MTOW.

- Now think through any later modifications you might want to make, what those will weigh, and add a bit more onto the MTOW.

- Outline design the main structural components (gear, mainplane, fuselage) to the MTOW, powerplant structure to the engine, tail feathers to match the performance, desired CG range, MTOW.

- Revise the empty weight estimates, decide whether you need to revise the MTOW, payload and performance targets at-all. The odds are you'll go around this loop quite a few times before you're reasonably happy that all the numbers line up.

- Now do the detailed design, build a structural prototype, and plan a set of physical tests - particularly on the mainplain (+Ve and -Ve g), engine mounts (torque, flight envelope, thrust, crash loads), any fuel tanks not built into in the wings, all of the control surfaces (equivalent of full deflection at Vc, 1/3 deflection at Vne), fin (max designed sideslip at Vne), horizontal stabiliser (MTOW, Fwd CG, Vne is usually the critical case). Based upon the test results some redesign might be needed, or some small changes to the MTOW might be needed.

- Finally, declare MTOW, build the flight test prototype, and then there will be some confirmation of MTOW compared to performance requirements. In practice however, very few aeroplanes - maybe the odd underpowered light twin or very old / small engined microlight are MTOW limited by performance - although I've met one or two. SEIO climb performance on twins, or mimimum time to 1000ft at ISA S/L standard conditions are generally the factors you're checking at. On a microlight or VLA designed too close to the stall speed limits, I suppose it's possible that too high a stall speed can also force reduction of MTOW, but that was a serious design cock-up if it does.



You weren't looking for a quick and simple answer I hope MJ?

G

[Mickey Kaye]

MJ - I see your point but but my limited exposure to Rotaxs in VLA in the training envoroemnt shows them to burn around 12 lts an hour and thats a hell of a saving compaired to an o-200 or o-235.

I also wonder if UL91 will cause a domino effect as if one school starts offering it then others will have to follow as they will not be able to compete from a price point of view.

Of course we could all just switch to C42 and then poor ASDA unleaded in and there has been a large drift in this direction over the last few years.

[Genghis the Engineer]

my limited exposure to Rotaxs in VLA in the training envoroemnt shows them to burn around 12 lts an hour and thats a hell of a saving compaired to an o-200 or o-235.

Something worth mentioning there - the 912 is a lot lighter than any of the usual Lycontinental lumps. Because the engine is such a large part of the aircraft's empty weight - put a lighter engine in, and you can make a lighter aeroplane, and the smaller lighter aeroplane will of course have a lower fuel burn. Lower fuel burn, means you need to carry less fuel, which brings fuel burn down again.

Aircraft design weights tend to spiral either inwards or outwards - the art is to make it spiral inwards.

G

[mrmum]

I fully expect C152's to be used in training until the day I die.
How old are you MJ? Also, are you a stereotypical "proper" Scot, deep-fried everything, washed down with copious amounts of scotch and heavy? ;)
Then maybe we can have a guess at your expected longevity.

[mrmum]

Wing Life Extension: Sterling Aviation (http://www.sterlingaviationtech.com/store/shop.mvc?Screen=PROD&Product_Code=SA500&Category_Code=001)
There is an option to extend the spar life by thousands of hours, quite costly though, obviously.

[Big Pistons Forever]

I have been flying the same flying school 1979 C 152 off and on since 1979, first as a PPL renter, then CPL and Instructor student and as an instructor. When I first flew it, it had 220 hrs total time, it now has 19,700 hrs and with a relatively new paint and interior refurb, looks and flies just fine. The flying school has planned to keep it to 25,000 hours and then reevaluate its future.

[Duchess_Driver]

Ours are relatively young then.... Our highest time is just over 14K. Regularly serviced, well maintained, repainted once in a while - new interiors when needed and the when time, a wash now and again!

In all seriousness - reliable, robust, repairable, versatile and more importantly, PAID FOR!

[RTN11]

I would assume the C152 would way out live the PA38. Even with the wing life extension the PA38 has no future, 1000 hours is barely two years for the average school.

The C152 will keep going until crashed and damaged beyond economical repair. They are currently so cheap to run and parts are so readily available that they make ideal trainers, as they always have. Perhaps with an obesity epidemic they will become less popular, unless people either willingly or unknowingly fly them over weight.

It's a shame, since the PA38 is in theory the perfect training aircraft, and I as far as I know the only civilian aircraft truely designed for the purpose of basic training. I wonder how many are still flying in the UK?

[Big Pistons Forever]

I read somewhere that the highest time Cessna single is a C 172 which flies 8 hours a day doing low level pipe line inspection. It has 36,000 hours and is still going strong.

Granted not exactly apples to apples but I used to regularly fly a Convair 580 that had 97,000 hours and 156,000 cycles.

A light Cessna that is well maintained has effectively an infinite life. It is corrosion and poor maintenance that kills these airplanes.

[Big Pistons Forever]

It's a shame, since the PA38 is in theory the perfect training aircraft, and I as far as I know the only civilian aircraft truely designed for the purpose of basic training. I wonder how many are still flying in the UK?

A perfect example of great intentions poorly executed. When Piper started developing the Pa 38 they consulted widely with working instructors and flight schools and stated that they wanted to indeed build the perfect training aircraft.

Then the marketing department insisted on the stupid T -tail and the accountants kept on demanding the engineers make it cheaper and the result turned out to be poor flying qualities, dozens of AD's, such bad build quality that 6 months from new the aircraft looked like it had spent years being abused in some African air force, and ultimately unviable economics for the flying schools that believed the hype.

Every school that used Pa 38's in Canada has now disposed of their fleet and almost all went back to the C 152.

[mad_jock]

Thanks for that DAR and G .